Foldable dialysis unit with integral pump and a method for performing solution exchange

ABSTRACT

A system and a method are provided to effect solution exchange particularly for a patient requiring peritoneal dialysis. The system includes a device (1) that is portable and particularly adaptable for patients requiring a night time exchange or an additional exchange. The device (1) includes an operator-touch control panel (10) operatively connected to a pouch (26) with an incorporated heater (12). The pouch (26) holds a solution bag (18) and may be selectively opened and closed by a cover (28). A drain tray (30) holds a drain bag (20) and has a scale (14) incorporated therein. The pouch (26) is connected to the control panel (10) by an upper arm (38), and the drain tray (30) is connected to the control panel (10) by a lower arm (42). The device (1) may be collapsed by releasing the upper arm (38) and the lower arm (42) such that the system (1) lays in a substantially flat arrangement when not in use.

BACKGROUND OF THE INVENTION

The present invention generally relates to a pumping system. Morespecifically, the present invention relates to a system and a method forpumping fluid, particularly for peritoneal dialysis.

As is well known, peritoneal dialysis is a procedure for removing toxicsubstances and metabolites normally excreted by the kidneys and foraiding in the regulation of fluid and electrolyte balance. Peritonealdialysis is accomplished by instilling peritoneal dialysis fluid througha conduit into a peritoneal cavity of an individual. The instilledperitoneal dialysis fluid contains ionic concentrations of electrolytesthat are similar to those in the physiological extracellular fluid withthe exception of lactate which is present as a bicarbonate precursor.

Fluid and solute transport occur across the peritoneal membrane betweenthe plasma of the patient and the instilled dialysis fluid. Theseprocesses result in normalization of plasma electrolyte profiles. Toxicsubstances and metabolites present in high concentrations in the bloodcross the peritoneal membrane into the dialyzing fluid. Dextrose, invarying concentrations, is used in the dialyzing fluid to produce asolution hyperosmolar to the plasma thus creating an osmotic gradientthat facilitates fluid removal from the patient's plasma into theperitoneal cavity.

After a period of time (dwell time), the spent or used dialysis fluid isremoved from the peritoneal cavity. Peritoneal dialysis is required forpatients with acute or chronic renal failure when non-dialytic medicaltherapy is judged to be inadequate.

One form of peritoneal dialysis, continuous ambulatory peritonealdialysis (CAPD) involves maintaining dialysis solution in constantcontact with the peritoneal membrane throughout the entire day. Toconduct CAPD, the patient manually drains spent dialysate and manuallyinstills new dialysate performing a number of necessary manipulationsduring the procedure. CAPD relies on gravity to move fluid in and out ofthe peritoneal cavity. The peritoneal dialysis solution is changedapproximately three to five times per day and typically four exchangesper day. Usually, three of these exchanges include dwell times of fourto six hours while an overnight exchange may include a dwell time ofeight to ten hours.

During the long, overnight dwell period, the efficiency of fluid removalmay be reduced if the osmotic gradient is lost due to uptake of dextroseinto the patient over time. Also, the ability of the dialysis fluid topromote clearance of uremic toxins is reduced once the concentration ofthe toxin in the dialysis fluid reaches the plasma concentration of theanalyte. Thus, removing spent fluid and replacing it with fresh dialysissolution (the addition of a fifth peritoneal dialysis exchange) duringthe overnight period may be helpful to patients requiring additionalfluid or toxin removal.

The present invention, therefore, provides a system and a method tosatisfy a need of patients requiring a fifth peritoneal dialysisexchange (during sleep) or for patients who desire a more convenientmethod to perform four exchanges per day by skipping one daytimeexchange. The present invention, therefore, provides a system and amethod for a night exchange that aids in removing peritoneal dialysissolution into and out of the patient and allows the patient additionalfreedom of movement during the procedure.

SUMMARY OF THE INVENTION

The present invention provides a system and a method for automaticcontrol of exchanged solutions, particularly for treatment of renalfailure patients undergoing peritoneal dialysis. The system provides adevice, particularly suitable for patients requiring a fifth dialysatesolution exchange. The device automatically drains spent fluid from theperitoneum and fills with a prescribed volume of peritoneal dialysisfluid warmed to body temperature.

To this end, in an embodiment, the present invention provides a systemfor controlling fluid flow. The system has a holder capable of holding afirst container having a first solution therein. A processor unit has ameans for controlling flow connected to the holder wherein the means forcontrolling flow is capable of controlling flow of the first solutionfrom the first container in the holder. A tray is provided capable ofholding a second container wherein the means for controlling flow iscapable of controlling flow of a second solution to the secondcontainer.

In an embodiment, a heater is incorporated in the holder capable ofheating the first solution in the first container in the holder.

In an embodiment, a scale is incorporated in the tray capable ofweighing the second container placed on the tray.

In an embodiment, the system includes a fill valve controlling flow ofthe first solution from the first container.

In an embodiment, the system includes a drain valve controlling flow ofthe second solution to the second container.

In an embodiment, an arm connects the holder to the processor unit.

In an embodiment, an arm connects the processor unit to the tray.

In an embodiment, a display is operatively connected to the processorunit.

In an embodiment, an input means is operatively connected to theprocessor unit.

In an embodiment, means are provided for effecting structuralrelationships between the holder and the processor unit.

In an embodiment, a cover is connected to the holder to substantiallyenclose the first container in the holder.

In an embodiment, a power switch is operatively connected to the tray toactivate the system.

In an embodiment, means are provided to alter position of the processorunit.

In an embodiment, means are provided to release the holder, theprocessor unit and the tray to orient in a non-operable position.

In an embodiment, an audible means is provided operatively connected tothe processor unit capable of producing an audible signal.

In an embodiment, an auxiliary processor is provided in the trayoperatively connected to the processor unit.

In an embodiment, a real time clock is operatively connected to theprocessor unit.

In an embodiment, a programmable timing means is operatively connectedto the processor unit to control activation of the system.

In an embodiment, operator-actuated keys are provided to controlprogramming of the processor unit. The operator-actuated keys aremodifiable by the processor unit.

In an embodiment, the means for controlling flow of the system is apneumatic pump.

In an embodiment, sensing means are provided for detecting temperatureof the first solution in the container.

In an embodiment, a plurality of strain gauges are constructed andarranged with the tray capable of measuring weight of the secondcontainer on the tray.

In another embodiment of the present invention, a method is provided forcontrolling fluid flow. The method comprises the steps of: providing aholder capable of holding a first container having a first solutionwithout hanging the first container; providing a tray capable of holdinga second container having a second solution without hanging the secondcontainer, the first container remotely situated from the secondcontainer; and controlling flow of the first solution from the firstcontainer and the flow of the second solution to the second container.

In an embodiment, the method further comprises the step of weighing thesecond solution in the second container without removing the secondcontainer.

In an embodiment, the method further comprises the step of heating thefirst solution in the holder.

In an embodiment, the method further comprises the step of selectivelyenclosing the first container in the holder.

In an embodiment, the method further comprises the step of sensingtemperature of the first solution in the first container.

In an embodiment, the method further comprises the step of controllingdraining of the first container and the filling of the second container.

In an embodiment, the method further comprises the step of draining thefirst container only after weighing the second container.

In an embodiment, the method further comprises the step of folding theholder and the tray into a second position not suitable for use.

In an embodiment, the method further comprises the step of providing adisplay indicative of performed functions.

In an embodiment, the method further comprises the step of providing acover to selectively enclose the first container in the holder.

In another embodiment of the present invention, a bag holder is providedhaving a container selectively openable to hold a bag therein. A coverencloses the container in the bag holder wherein the cover is hinged tothe container. A heating element is incorporated in the containercapable of heating a solution in the bag.

In an embodiment, the bag holder further has an opening in the containerthrough which an extension of the cover is inserted wherein the cover ispivotable at the opening.

In an embodiment, the heating element is a film etched in the container.

In an embodiment, a sensor is incorporated with the heating element todetect temperature variations of the solution in the bag.

In an embodiment, the container of the bag holder is insulated.

In another embodiment of the present invention, a portable peritonealdialysis exchange system is provided. The system has a drain traycapable of holding a drain bag without hanging the drain bag. A pouch iscapable of holding a solution bag without hanging the solution bag. Acollapsible linkage connects the drain tray to the pouch, and aprocessor having a flow control means is operatively connected to thedrain bag and the solution bag to control flow of fluid to the drain bagfrom a patient and from the solution bag to the patient.

In an embodiment, the system has a scale incorporated in the drain trayto measure weight of the drain bag.

In an embodiment, the system has a heating means incorporated in thepouch to effect heating of the solution bag and its contents.

In an embodiment, valves are associated with the processor to assist theflow control means to control flow of fluids.

In an embodiment, the processor of the system is constructed andarranged between the drain tray and the pouch wherein the pouchgravitationally feeds fluid from the solution bag toward the processor.

In an embodiment, a display is associated with the processor displayingfunctions of the processor.

In an embodiment, keys are associated with the processor to controlprogrammable functions of the processor.

In an embodiment, a cover is constructed and arranged to selectivelyopen and close the pouch.

In an embodiment, means for adjusting orientation of the processorwithout affecting the orientation of the pouch is provided.

In an embodiment, a handle is constructed and arranged on the linkage toselectively effect collapse of the linkage.

It is, therefore, an advantage of the present invention to provide asystem and a method for solution exchange that is simple to use.

Yet another advantage of the present invention is to provide a systemand a method for solution exchange that is convenient to use.

A further advantage of the present invention is to provide a system anda method for solution exchange that is cost-effective to use.

A still further advantage of the present invention is to provide asystem and a method for solution exchange that requires use of aportable device.

Moreover, an advantage of the present invention is to provide a systemand a method for solution exchange particularly suitable for patientsrequiring peritoneal dialysis.

And, another advantage of the present invention is to provide a systemand a method for solution exchange that may be performed during thenight time and/or while a patient is sleeping.

A further advantage of the present invention is to provide a system anda method for solution exchange that is programmable.

A still further advantage of the present invention is to provide asystem and a method for solution exchange that is compact so as to beeasily stowed.

And, another advantage of the present invention is to provide a systemand a method for solution exchange capable of heating a solution usingminimal power and minimizing heat loss.

Moreover, an advantage of the present invention is to provide a systemand a method for solution exchange that prevents filling of one solutionprior to draining of a second solution.

Another advantage of the present invention is to provide a system and amethod for solution exchange that is safe to use.

Yet another advantage of the present invention is to provide a systemand a method for solution exchange that provides suitable alarmconditions to notify a patient of conditions or failure in the system.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the detailed description of thepresently preferred embodiments and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a front perspective view of an embodiment of thesystem of the present invention.

FIG. 2 illustrates a perspective view with one arm folded up in anembodiment of the system of the preset invention.

FIG. 3 illustrates a rear perspective view of an embodiment of thesystem of the present invention.

FIG. 4 illustrates a perspective view of the system of the presentinvention in its collapsed or folded position.

FIG. 5 illustrates an environmental view of the general flowrequirements of solutions to and from a patient requiring peritonealdialysis.

FIG. 6 illustrates a black box diagram of the hardware components in anembodiment of the present invention.

FIG. 7 illustrates a circuit diagram of the pneumatics required for thesystem in an embodiment of the present invention.

FIG. 8 illustrates a general flow chart of a structure of the mainprogram to operate the system and method of an embodiment of the presentinvention.

FIG. 9 illustrates perspective views of various user interface screensdisplayed by an embodiment of the system of the present invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

The present invention provides a system for automatic control ofdialysate solution exchange in treatment of chronic renal failurepatients undergoing peritoneal dialysis. The system includes a machinethat automatically drains spent fluid from the peritoneum then fills thesame with a prescribed volume of peritoneal dialysis fluid warmed tobody temperature. The device fills the need for patients who require aperitoneal dialysis exchange, such as a fifth exchange, night timeexchange, or those patients requiring a more convenient time and methodfor performing four exchanges by skipping one day time exchange.

The system is designed for use with a peritoneal dialysis solutioncontainer, such as, for example, a Dianeal™ peritoneal dialysis solutionin an Ultrabag™ container manufactured and sold by Baxter HealthcareCorporation of Deerfield, Ill. Such a container consists of a solutionbag, administration tubing and a drain bag. Other similar twin bagsystems may be implemented with the system of the present invention.

A sterile fluid path of the twin bag transfers the peritoneal dialysissolution to and from a patient during the dialysis treatment. Anextension line may further be provided to lengthen the fluid pathallowing the patient more freedom of movement once connected to thesystem. Such an extension line is typically a single use product.

Referring now to the drawings wherein like numerals refer to like parts,an embodiment of an exchange system of the present invention isgenerally designated at 1. The system 1 includes four principalcomponents: an operator touch control panel 10, an insulated heater 12incorporated in a pouch 26, a scale 14 incorporated in a drain tray 30and at least two automated valves 16a, 16b.

As illustrated in FIG. 1, a solution bag 18 is provided within the pouch26 including the insulated heater 12, and a drain bag 20 is laid on thedrain tray 30 including the scale 14. Administration tubing 22 connectsthe drain bag 20 and the solution bag 18 with the system 1 and theautomated valves 16a, 16a. An extension line tubing 24 connects to theadministration tubing 22 and extends to a patient 2 (as shown in FIG. 5)subjected to the peritoneal dialysis procedure.

Referring now to FIG. 5, a fluid flow diagram demonstrating how thesystem 1 of the present invention cycles fluid into and out of a patient2 is shown. To this end, the system 1 consists of the two automatedvalves 1; one valve 16a is a fill valve between the solution bag 18 andthe extension line 24 and the other valve 16a is a drain valve betweenthe extension line tubing 24 and the drain bag 20. The administrationtubing 22 connects the valves 16a and 16a to the solution bag 18 and thedrain bag 20, respectively.

Referring again to FIGS. 1-4, the exchange system 1 generally consistsof a collapsible S-shaped pole with three distinct areas: a top portion,a bottom portion and a middle portion. The top portion of the exchangesystem 1 includes the insulated heater 12 incorporated in a shell of thepouch 26 for holding the solution bag 18. The pouch 26 is insulated andincludes the heater 12 designed to slowly warm the solution bag 18 andthe solution therein to a temperature approximately equal to bodytemperature. The solution bag 18 is loaded into the pouch 26 with theadministration tubing 22 exiting a bottom end of the pouch 26. A cover28 encloses the pouch 26 holding the solution bag 18. The cover 28 maybe folded to enclose the pouch 26 as illustrated in FIGS. 2 and 4.

The bottom portion of the exchange system includes the drain tray 30with the scale 14 incorporated therein. The scale 14 is capable ofmeasuring a weight of the fluid drained into the drain bag 18 that isfed from the administration tubing 22 into the drain bag 20. The drainbag 20 may be placed on the drain tray 30 in any position to determinethe weight of the drain bag 20 using the incorporated scale 14. Asillustrated in FIG. 1, the drain bag 20 is centrally located on thedrain tray 30.

Finally, the middle portion includes the operator touch control panel 10and the automated clamps or valves 16a,16a. The operator touch controlpanel 10, in a preferred embodiment, is an LCD display 54 provided withvarious sized fonts and icons making the exchange system 1 easy-to-useand flexible for various language formats. To this end, three keys 34are provided allowing input of information.

Two notched areas 36 are also provided to accept the administrationtubing 22. The notched area 36 includes the valve 16a that controlsfluid flow from the solution bag 18 through the extension line tubing 24and to the patient 2 while the other notched area 36 includes the valve16a and receives solution from the patient 2 and drains the same to thedrain bag 20 on the drain tray 30. Preferably, the administration tubing22 from the solution bag 18 goes through the top notched area 36 whilethe bottom notched area 36 receives the administration tubing 22 leadingto the drain bag 20.

Connecting the top portion to the middle portion is an upper arm 38. Arelease handle 40 is provided along a length of the upper arm. Therelease handle 40 includes a lever requiring manipulation to fold theexchange system 1 for storage or transport. A lower arm 42 connects themiddle portion with the lower portion. A power switch 44 is preferablyprovided on the lower portion adjacent the drain tray 30 to activate anddeactivate the exchange system 1.

Referring to FIG. 3, the exchange system 1 includes an upper knuckle 46at the middle portion opposite a face of the operator touch controlpanel 10. The upper knuckle 46 includes a tilt adjuster 48 that adjuststhe view angle of the operator touch control panel 10. The lower knuckle50 is provided at the lower portion of the exchange system 1 andconnects the lower arm 42 to the drain tray 30. The upper knuckle 46connects the upper arm 38 to the lower arm 42 and also connects theoperator touch control panel 10 therebetween. A detachable power cord 52is connected to the lower portion at the drain tray 30.

Referring now to FIG. 4, the fill valve 16a and the drain valve 16a areshown adjacent the operator touch control panel 10. The fill valve 16aconnects to the administration tubing 22 that connects to the solutionbag 18. The fill valve 16a controls flow of solution from the solutionbag 18 to the patient 2. Similarly, the drain valve 16a is at a locationwhere the drain line is inserted and is capable of controlling the flowof solution from the patient 2 to the drain bag 20 on the drain tray 30.

The operator touch control panel 10 includes the display 54. The display54 displays information with respect to set-up of the exchange system 1prior to use. During use, the display 54 displays information withrespect to progress of treatment. The control keys 34, in conjunctionwith the display 54, of the operator touch control panel 10 are used forset-up for treatment.

To use the exchange system 1, a well-lit area with a clean, flat surfaceis preferred. The exchange system 1 is particularly adaptable for homeuse, particularly for patients who require an exchange at night.Therefore, a night stand or a table near a bed of the patient istypically a good choice for setting up the system 1. An outlet isfurther required for plugging in the power cord 52 to provide power torun the exchange system 1.

To operate the exchange system 1, the bag 18 containing a solution, suchas Dianeal™, distributed by Baxter Healthcare Corporation of Deerfield,Ill., may be used with a separate or pre-attached set. A prep kit ordisconnect cap as well as any other accessories typically required forperforming a CAPD exchange are also necessary. An extension set isfurther required, such as the extension line tubing 24.

The exchange system 1 is typically stored in the position illustrated inFIG. 4. To set up the exchange system 1, the lower arm 42 is raised tothe position shown in FIG. 2. The upper arm 38 may then be pulled tounfold the exchange system 1 into an upright position as illustrated inFIGS. 1 and 3. The upper knuckle 46 and the lower knuckle 50 aredesigned such that the exchange system 1 remains in position and willnot collapse prior to full extension of the upper arm 38 and the lowerarm 42.

After the exchange system 1 is converted to the position illustrated inFIGS. 1 and 3, the power cord 52 is plugged into a grounded outlet. Thesolution bag 18 and the drain bag 20 with the fill line and the drainline as part of the administration tubing 22 may then be loaded into thesystem 1 as illustrated in FIG. 1. The extension line tubing 24 may beattached to the administration tubing 22 for connection to a patient. Tothis end, the fill line of the administration tubing 22 is pressed ontothe fill valve gate at the location of the automated valve 16a. Tubingis inserted into the slots, and the automated fill valve 16a with itsgate springs back into its original position. The drain line issimilarly inserted into the drain valve 16b.

Prior to initial set-up, the power switch 44 turns on the system andinstructions are provided for each step required to set up the system 1.That is, the display, following power-up provides the message "LOAD SETAND ATTACH EXTENSIONS". The display 54 includes a real time clock and aprogrammable time to activate the exchange. The display 54, followingset-up, provides instructions, such as the following: "CONNECT SET,BREAK FRANGIBLES AND VERIFY FLOW". These instructions indicate to theuser or administrator that an auto-flush procedure will take place. Thisinitiates fluid flow from the fill bag to the drain. After the flushfrom the fill bag has been completed, the display 54 will read "OPENTRANSFER SET". The patient transfer set clamp is then opened.

At this point, fluid from the patient flows from the drain bag. Thedrain valve 16b then closes after an appropriate flush volume has beendetected on the drain tray. Then, the patient can go to bed.

During the night, an exchange takes place at the designated timeprogrammed on the display 54. Therefore, following flushing, the display54 indicates that the flush is complete ("FLUSH COMPLETE") and furtherindicates that set-up is complete by providing an appropriate messagesuch as "GOOD NIGHT." At the programmed time, for example, 2:00 a.m.,the exchange system 1 opens the drain valve 16b and drains the fluidfrom the patient's peritoneal cavity into the drain bag 20. After thedrain is complete, the system 1 opens the fill valve 16a, and freshsolution flows into the peritoneal cavity. During this time, the display54 may provide an indication of the amount of fluid in the drain bag 20by that information sensed and transmitted by the scale 14 incorporatedwithin the drain tray 30.

The following day, the patient 2 can touch any of the keys 34 on thecontrol panel 10, and the display 54 will activate. The patient 2 isthen instructed by the display 54 of the operator touch control panel 10to "CHECK FILL BAG", "ATTACH CLAMPS", and "CLOSE TRANSFER SET AND CAPOFF." Therefore, the patient 2 is required to be attached to clamps andto each line to eliminate spilling during removal and to open a newdisconnect cap and to cap off the transfer set. The disposable is thenremoved and discarded using normal procedures required for CAPD. An"UNLOAD" instruction is then provided, and an indication of the drainvolume may be displayed as well.

The exchange system 1 may then be put away by the patient 2 by pressingthe release handle 40 and pressing down simultaneously on the upper arm38. The lower arm 42 simultaneously releases such that the exchangesystem 1 is forced to the position as illustrated in FIG. 4.

The operator touch control panel 10 allows a user to program a number oftherapy parameters. For example, the exchange time, the drain time, theset time, the set date and the previous fill volume may all beprogrammed. The display 54 provides step-by-step instructions foreffecting programming of each parameter using only the three keys 34adjacent the display 54 on the operator touch control panel 10.

The operator touch control panel 10 may also include an alarm 56 or anaudio prompt or other features as required by the system 1. Whenever theexchange system 1 identifies a problem in the system 1, the system 1 maysound an alarm and may immediately stop moving solution. The type ofalarm may be displayed. Two basic types of alarms may occur duringtherapy: an alarm capable of correction by the patient or with minimalassistance prompt and aid or an alarm indicative of system error causedby a problem within the exchange system 1. Following an alarm, thedisplay 54 prompts the patient or user to correct the condition. Anumber of alarm messages may be displayed on the display 54 andappropriate trouble shooting messages may follow. Examples of such alarmmessages include "CHECK DRAIN LINE", "CHECK DRAIN TRAY", "CHECK FILLLINE", "CHECK HEATER BAG", "CHECK PATIENT LINE", "DRAIN NOT COMPLETE"and "SYSTEM ERROR."

The heater 12 incorporated in the insulated pouch 26 of the exchangesystem 1 is connected at a top end of the upper arm 38 and is providedby an aluminum plate with a resistive heating element and a thermallyinsulated enclosure to receive the solution bag 18. A thermal circuitinterrupting device is mounted on the heater plate and shuts down theheater in the event of a thermal run away condition.

Referring now to FIG. 6, a block diagram of the electronics necessaryfor operating the exchange system 1 is illustrated. A processor 58 isprovided and mounted within the operator touch control panel 10. Theprocessor 58 monitors all inputs to the system 1 and controls thedisplay 54, the valves 16a, 16b, the heater 60, the pump and othersubsystems, such as the alarm 56.

An auxiliary processor 62 may be provided and located in the baseplatform of the drain tray 30. The auxiliary processor 62 is used as aslave device to implement certain control and monitoring functions ofcomponents, particularly at the location of the drain tray 30. Theprimary purpose of the auxiliary processor 62, however, is to minimizethe amount of interconnect cabling required between the operator touchcontrol panel 10 and the base portion at the drain tray 30.

The fill and drain valves 16a and 16b, respectively, operate by apneumatic system requiring a pneumatic circuit as illustrated in FIG. 7.The pneumatic circuit is generally designated at 64 in FIG. 7 andincludes a pneumatic pump 66 driven by a motor 68. The pump 66 isconnected to three solenoid-type pneumatic valves 70, 72 and 74. Thethree solenoid-type valves 70, 72 and 74 are located in the base portionunder the drain tray 30 and provide routing of air pressure to the twovalves 16a and 16b located in the operator touch control panel 10 viatwo pneumatic tubes between the base portion and the panel 10.

To open the fill valve 16a, the pneumatic pump 66 is first turned onwith the main solenoid valve 70 in the vented position to allow the pump66 to start-up. Following start-up of the pump 66, the fill solenoidvalve 72 and the main solenoid valve 70 are opened. Pressure builds in apinch valve diaphragm and the valves open. When the valve positionsindicate that the valve is open, the main solenoid valve 70 is placedback in the vented position, and the pump 66 is turned off. To close thefilled solenoid valve 72, the filled solenoid valve 72 is placed in thevented position.

The drain solenoid valve 74 operates in a similar manner as the fillsolenoid valve 72. The valves 16a, 16b are spring-loaded, and thesolenoid valves are normally vented when not energized so that thespring will assure that the valves will fail in the closed position.

Preferably, the main processor 58 and the auxiliary processor 62 controland monitor all operations of the exchange system 1. The main processor58 is preferably a master sixteen-bit microcontroller, and the auxiliaryprocessor 62 is preferably a slave eight-bit microcontroller. Thesoftware architecture is shown in FIG. 8 after the system 1 isinitialized as generally designated at 100, for concurrently runningtasks 102, 104, 106 and 108. These tasks include interrupt tasks 102,monitor tasks 104, control tasks 106 and treatment tasks 108.

All tasks in this system can be classified as either control tasks,monitor tasks, or interrupt tasks. Interrupt tasks are operations toeffect a change in a physical component such as, for example, thevalves, the heater, the pump and/or the display panel. Monitor tasks areoperations that read the status of physical components such astemperature, fluid, the position of valves or user keys. Control andmonitor tasks are not intertwined as is usually done in single-threadedsoftware. On the contrary, a clear software boundary is defined betweencontrol and monitor functions to provide a completely modular and easilyverifiable software. The modules communicate with each other withrelatively few global variables. Therefore, changes in one module areprevented from adversely propagating to other modules. The interrupttasks are generated by either external or internal conditions and mustbe serviced immediately.

The main processor 58 and the auxiliary processor 62 are linked througha serial peripheral interface. The master-slave protocol consists of adata-in, data-out, data-clock and a slave-select line. The mainprocessor 58 acts as the master and orchestrates the entirecommunication. By selecting the auxiliary processor 62 as the slave, thetwo processors 58,62 exchange eight bits of data. For master-to-slave,this is a command byte; for slave-to-master, this is an input data byte.If a longer command or data transfer is necessary, a simple multi-byteprotocol may be used.

To ensure data integrity, additional safeguards are built on top of thebasic serial peripheral interface protocol. Periodically, the twoprocessors 58,62 exchange time stamps so that if, for some reason,either processor 58 or 62 is not performing as required, the otherprocessor detects the same and an orderly fault recovery can beattempted.

As previously discussed, the operator touch control panel 10 includesthe operator keys 34 provided for a user to interact with the exchangesystem 1. In a preferred embodiment, the keys are "soft" keys that haveno designation on the actual membrane of the key 34, but rather aredefined by software on the panel 10 directly above the actual key 34.The key definition will change based on the state of the system 1 atthat time. The key 34 may be back lit and the intensity of the key backlight varies along with intensity of the back light of the display 54.In addition to the three visible keys, two invisible keys are availablefor entry into service and nurse's menus, for example.

The display 54 is further provided for communication with the user. Thedisplay 54, in a preferred embodiment, has 302×240 pixels in a graphicsmode and 40×30 characters in a text mode. Text and graphics may,however, be overlaid for greater flexibility. The display 54 may be backlit by a cold cathode fluorescent tube (CCFT), the intensity of which isvariable under software control. The contrast is also variable undersoftware control.

The alarm 56 and audio system is provided for audible feedback to thepatient. Every press of the keys 34 results in a short audible tone. Anyuser set-up errors that are detected will result in a distinctive toneto prompt the user to look at the display 54 for instructions oncorrecting the set-up error. The service menu and the nurse's menu areaccessed by holding down certain key combinations at the time ofpower-up. Access to these menus is not possible at any other time.

FIG. 9 illustrates an overview of the user interface screens for thedisplay 54, The orientation of the soft keys is also shown with theirvariable designations defined by the software of the system 1.

The scale 14 of the exchange system 1 in the drain tray 30 includesforce sensing resistors (not shown). Force applied to the resistorscauses the resistance to change. The more force applied, the lower theresistance becomes. If the force sensing resistors are placed in asimple voltage divider circuit, a certain force gives a repeatablevoltage from the divider. The four sensing resistors can then becalibrated by running the system through an entire range of force andrecording the corresponding voltage. Using the set of calibrationvoltages, the force on the force sensing resistors can be determined forall subsequent runs. Of course, other known scales may be implemented tomeasure the rate of the drain bag 20 on the drain tray 30.

The insulated heater 12 within the pouch 26 may include internal sensors(not shown) to monitor the temperature of the foil heater assembly. Theinternal sensors can be tested for accuracy in linearity by applyingpower to the heater element and monitoring the response of the sensors.Due to intrinsic properties of the nickel iron material of the elementand the sensors, as the temperature increases, so does theirresistances. If the sensor is placed in a bridge circuit, the change inresistance can be directly related to a change in voltage. The sensorsare special traces etched onto the heater at the same time and of thesame material as the heater trace itself. The sensor is a thinequivalent of the heater trace causing its resistance to be higher. Whentemperature increases, the resistance of the trace increases. Theincrease is detected by a bridge circuit which amplifies the change.

The exchange system 1, therefore, provides a simple, convenient andcost-effective device for providing an additional exchange during thenight time. The system 1 satisfies a need for patients who require afifth CAPD exchange or patients who desire a more convenient method ofperforming four exchanges. The system 1 is portable and performs anexchange using a twin bag using an extension line. The system 1 has twoautomated valves, ensures drain before fill and provides a simple userinterface and an insulated heater to raise and maintain fluidtemperature.

Although the present invention has been described with reference to aperitoneal dialysis procedure, it should be understood that the presentinvention is adaptable to other fluid control systems, such asintravenous feeding.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications may be madewithout departing from the spirit and scope of the present invention andwithout diminishing its attendant advantages. It is, therefore, intendedthat such changes and modifications be covered by the appended claims.

I claim:
 1. A system for controlling fluid flow, the system comprising:aholder capable of holding a first container having a first solutiontherein; a processor unit having an integral pump connected to theholder wherein the pump is capable of pumping the first solution fromthe first container in the holder; a tray capable of holding a secondcontainer wherein the pump is capable of pumping a second solution tothe second container; and an arm connecting the holder to the processorunit wherein the arm includes a hinge at a point of connection to theprocessor unit such that the arm is rotatable with respect to theprocessor unit.
 2. The system of claim 1 further comprising:a heaterincorporated in the holder capable of heating the first solution in thefirst container in the holder.
 3. The system of claim 1 furthercomprising:a scale incorporated in the tray capable of weighing thesecond container placed on the tray.
 4. The system of claim 1 whereinthe means for controlling flow includes a fill valve controlling flow ofthe first solution from the first container.
 5. The system of claim 1wherein the means for controlling flow includes a drain valvecontrolling flow of the second solution to the second container.
 6. Thesystem of claim 1 further comprising:an arm connecting the processorunit to the tray.
 7. The system of claim 1 further comprising:a displayoperatively connected to the processor unit.
 8. The system of claim 1further comprising:an input means operatively connected to the processorunit.
 9. The system of claim 1 further comprising:means for effecting astructural relationship between the holder and the processor unit. 10.The system of claim 1 further comprising:a cover connected to the holderto substantially enclose the first container in the holder.
 11. Thesystem of claim 1 further comprising:a power switch operativelyconnected to the tray to activate the system.
 12. The system of claim 1further comprising:means to alter position of the processor unit. 13.The system of claim 1 further comprising:means to release the holder,the processor unit and the tray to orient in a non-operable position.14. The system of claim 1 further comprising:an audible meansoperatively connected to the processor unit capable of producing anaudible signal.
 15. The system of claim 1 further comprising:anauxiliary processor in the tray operatively connected to the processorunit.
 16. The system of claim 1 further comprising:a real time clockoperatively connected to the processor unit.
 17. The system of claim 1further comprising:programmable timing means operatively connected tothe processor unit to control activation of the system.
 18. The systemof claim 1 further comprising:operator-actuated keys to controlprogramming of the processor unit.
 19. The system of claim 18 whereinthe operator-actuated keys are modifiable by the processor unit.
 20. Thesystem of claim 1 wherein the means for controlling flow is a pneumaticpump.
 21. The system of claim 1 further comprising:sensing means fordetecting temperature of the first solution in the container.
 22. Thesystem of claim 1 further comprising:a plurality of strain gaugesconstructed and arranged with the tray capable of measuring weight ofthe second container on the tray.
 23. A method for controlling fluidflow, the method comprising the steps of:providing a holder capable ofholding a first container having a first solution therein withouthanging the first container; providing a tray capable of holding asecond container having a second solution therein without hanging thesecond container, the first container remotely situated from the secondcontainer; controlling pumping of the solution from the first containerand pumping of the second solution to the second container; and foldingthe holder and the tray into a second position not suitable for usewherein a first arm is connected to a second arm by a hinge wherein thefirst arm and the second arm are rotatable with respect to each other atthe hinge.
 24. The method of claim 23 further comprising the stepof:weighing the second solution in the second container without removingthe second container.
 25. The method of claim 23 further comprising thestep of:heating the first solution in the holder.
 26. The method ofclaim 23 further comprising the step of:selectively enclosing the firstcontainer in the holder.
 27. The method of claim 23 further comprisingthe step of:sensing temperature of the first solution in the firstcontainer.
 28. The method of claim 23 further comprising the stepof:controlling draining of the first container and the filling of thesecond container.
 29. The method of claim 23 further comprising the stepof:draining the first container only after weighing the secondcontainer.
 30. The method of claim 23 further comprising the stepof:providing a display indicative of performed functions.
 31. The methodof claim 23 further comprising the step of:providing a cover toselectively enclose the first container in the holder.
 32. The method ofclaim 23 wherein the control of flow is performed by pneumatic pumping.33. A portable peritoneal dialysis exchange system comprising:a draintray capable of holding a drain bag without hanging the drain bag; apouch capable of holding a solution bag without hanging the solutionbag; a collapsible linkage connecting the drain tray to the pouch; and aprocessor with a pumping means operatively connected to the drain bagand the solution bag to automate pumping of fluid to the drain bag froma patient and from the solution bag to the patient wherein thecollapsible linkage includes a first arm extending between the pouch andthe processor and a second arm extending between the processor and thedrain tray wherein a hinge connects the first arm to the second arm andfurther allows each arm to rotate at the hinge.
 34. The system of claim33 further comprising:a scale incorporated in the drain tray to measureweight of the drain bag.
 35. The system of claim 33 further comprising:aheating means incorporated in the pouch to effect heating of thesolution bag and its contents.
 36. The system of claim 33 wherein thepouch is insulated.
 37. The system of claim 33 further comprising:valvesassociated with the processor to assist the flow control means tocontrol flow of fluids.
 38. The system of claim 33 wherein the processoris constructed and arranged between the drain tray and the pouch, thepouch gravitationally feeding fluid from the solution bag toward theprocessor.
 39. The system of claim 33 further comprising:a displayassociated with the processor displaying functions of the processor. 40.The system of claim 33 further comprising:keys associated with theprocessor to control programmable functions of the processor.
 41. Thesystem of claim 33 further comprising:a cover constructed and arrangedto selectively open and close the pouch.
 42. The system of claim 33further comprising:means for adjusting orientation of the processorwithout affecting the orientation of the pouch.
 43. The system of claim33 further comprising:a handle constructed and arranged on the linkageto selectively effect collapse of the linkage.
 44. A system forcontrolling fluid flow, the system comprising:a holder capable ofholding a first container having a first solution therein; a processorunit having an integral pump connected to the holder wherein the pump iscapable of pumping the first solution from the first container in theholder; a tray capable of holding a second container wherein the pump iscapable of pumping a second solution to the second container; and acover connected to the holder to substantially enclose the firstcontainer in the holder.
 45. A system for controlling fluid flow, thesystem comprising:a holder capable of holding a first container having afirst solution therein; a processor unit having an integral pumpconnected to the holder wherein the pump is capable of pumping the firstsolution from the first container in the holder and further wherein thepump is pneumatic; and a tray capable of holding a second containerwherein the pump is capable of pumping a second solution to the secondcontainer.
 46. A method for controlling fluid flow, the methodcomprising the steps of:providing a holder capable of holding a firstcontainer having a first solution therein without hanging the firstcontainer; providing a tray capable of holding a second container havinga second solution therein without hanging the second container, thefirst container remotely situated from the second container; controllingpumping of the solution from the first container and pumping of thesecond solution to the second container; selectively enclosing the firstcontainer in the holder.
 47. A method for controlling fluid flow, themethod comprising the steps of:providing a holder capable of holding afirst container having a first solution therein without hanging thefirst container; providing a tray capable of holding a second containerhaving a second solution therein without hanging the second container,the first container remotely situated from the second container;controlling pumping of the solution from the first container and pumpingof the second solution to the second container; and providing a cover toselectively enclose the first container in the holder.
 48. A method forcontrolling fluid flow, the method comprising the steps of:providing aholder capable of holding a first container having a first solutiontherein without hanging the first container; providing a tray capable ofholding a second container having a second solution therein withouthanging the second container, the first container remotely situated fromthe second container; and controlling pumping of the solution from thefirst container and pumping of the second solution to the secondcontainer wherein the pumping is performed pneumatically.
 49. A portableperitoneal dialysis exchange system comprising:a drain tray capable ofholding a drain bag without hanging the drain bag; a pouch capable ofholding a solution bag without hanging the solution bag; a collapsiblelinkage connecting the drain tray to the pouch; and a processor with apumping means operatively connected to the drain bag and the solutionbag to automate pumping of fluid to the drain bag from a patient andfrom the solution bag to the patient; and a cover constructed andarranged to selectively open and close the pouch.